Pollinator decline is based on an observation made at the end of the twentieth century, which is the reduction in abundance of pollinators in many ecosystems worldwide.
Pollinators participate in sexual reproduction of many plants, by ensuring cross-pollination, essential for some species, or a major evolutionary factor for others. Since plants are the primary food source for the all animals, the reduction of one of the primary pollination agent, or even their possible disappearance, has raised concern, and the conservation of pollinators has become part of biodiversity conservation efforts.
As plantings have grown larger, the need for concentrated pollinators at bloom time has grown. At the same time populations of many pollinators has been declining, and this decline has become a major environmental issue today. Pollination management seeks to protect, enhance, and augment agricultural pollination.
For example, feral honeybee populations in the US have dropped about 90% in the past 50 years, except for the Southwest where they have been replaced by africanized bees. At the same time managed honeybee colonies have dropped by about two thirds.
Monoculture needs very high populations at bloom, but can make the area quite barren, or even toxic when the bloom is done.
The study of pollinator decline is also interesting some scientists, as bees have the potential to become a keystone indicator of environmental degradation. Any changes in their abundance and diversity will influence the abundance and diversity of the prevailing plant species.
The value of bee pollination in human nutrition and food for wildlife is immense and difficult to quantify.
It is commonly said that about one third of human nutrition is due to bee pollination. This includes the majority of fruits, many vegetables (or their seed crop) and secondary effects from legumes such as alfalfa and clover fed to livestock.
In 2000 Drs. Roger Morse and Nicholas Calderone of Cornell University, attempted to quantify the effects of just one pollinator, the honeybee, on only US food crops. Their calculations came up with a figure of US $14.6 billion in food crop value.
There has not been sufficient study to quantify the effects of pollinator decline on wild plants and wild life that depends on them for feed. Some plants on the endangered species list are endangered because they have lost their normal pollinators.
The steady increase in beekeeper migration has masked the issue of pollinator decline from much public awareness, however sudden blocks to such migration could have catastrophic results on the US food supply.
It is a label violation to apply most insectides on crops during bloom, or to allow the pesticide to drift to blooming weeds that bees are visiting. Yet such applications are frequently done, with little enforcement of the bee protection directions. Pesticide misuse has driven beekeepers out of business, but can affect native wild bees even worse, because they have no human to move or protect them.
Bumblebee populations are in very bad shape in cotton-growing areas. Bumbles are hit over and over when pesticide applicators apply insecticides on blooming cotton fields while the bees are foraging.
Widespread aerial applications for mosquitoes, med-flies, grasshoppers, gypsy moths and other insects leaves no islands of safety where wild insect pollinators can reproduce and repopulate. One such program can knock down pollinator populations for several years.
The chemlawn philosophy has convinced people that dandelions and clover are weeds, that lawns should only be grass, and that they should be highly treated with pesticides. This makes a hostile environment for bees, butterflies and other pollinators.
Increased international commerce within modern times has moved diseases such as American foulbrood and chalkbrood, and parasites such as varroa mites, acarine mites, and the small African hive beetle to new areas of the world, causing much loss of bees in the areas where they do not have much resistance to these pests. Imported fire ants have decimated ground nesting bees in wide areas of the southern US.
The push to remove hedgerows and other "unproductive" land in some farm areas removes habitat and homes for wild bees. Large tractor mounted rotary mowers may make farms and roadsides look neater, but they remove bee habitat at the same time. Old crops such as sweet clover and buckwheat, which were very good for bees have been disappearing. Urban and suburban development pave or build over former areas of pollinator habitat. Migratory pollinators, such as monarch butterflies and some hummingbirds depend on nectar corridors for their annual migration, and development or agricultural practices have disrupted some of these vital corridors.
Clearcut logging, especially when mixed forests are replaced by uniform age pine planting, causes serious loss of pollinators, by removing hardwood bloom that feeds bees early in the season, and by removing hollow trees used by feral honeybees, and dead stubs used by many solitary bees.
If one runs a seach for "carpenter bees" the Internet, one will mostly find information about how to kill these valuable pollinators, not how to encourage and use them. This attitude ("Get the bug spray, ma, I just saw a bee!") is one of the worst problems our pollinators have. The "killer bee" hype has increased this paranoia. Beekeepers find increased vandalism of their hives, more difficulty in finding locations for bee yards, and more people inclined to sue the local beekeeper if they are stung, even if it is by a yellow jacket.
Increasing use of outside artificial lights, which interfere with the navigational ability of many moth species, and is suspected of interference with migratory birds may also impact pollination. Moths are important pollinators of night blooming flowers and moth disorientation may reduce or eliminate the plants ability to reproduce, thus leading to long term ecological effects. This is a new field and this environmental issue needs further study.
The decline of pollinators is compensated to some extent by beekeepers becoming migratory, following the bloom northward in the spring from southern wintering locations.
Efforts made to sustain pollinator diversity in agro- and natural eco-systems.
Honey bees are usually the most widely chosen insects in most managed pollination situations. However, some specialists believe they are not the most efficient pollinators, and could be replaced by alternative pollinators, such as for example, leafcutter and alkalai bees in alfalfa pollination and bumblebees in greenhouses for tomatoes. A wide variety of other bees can be found in the environment that are specialist pollinators. However, most of these alternative insects value as pollinators and their relationships with plants are as yet little known.
Some think that other pollinators will in time replace the lost honeybees, but general pollinator decline was already happening before diseases such as acarine and varroa mites decimated honeybees. Only in a few areas, wild populations of pollinators are building up; in most areas they are declining as badly as honeybees.
Furthermore pollinators cannot be exchanged on a one for one basis. They are not all equal. Some are generalists, some are specialists. Some have long tongues; some short. Bees may deliberately collect pollen, but have different collection techniques, which can greatly affect their efficiency as pollinators.
Observation of pollinator decline
Consequences
Increasing public awareness
Possible explanations for pollinator decline
Pesticide misuse
the Gaucho and Regent cases
Rapid transfer of parasites and diseases around the world
Loss of habitat and forage
Bee paranoia
Light pollution
Solutions to pollinator decline
Conservation and restoration efforts
Use of alternative pollinators
See also
References
